The present invention relates to electrical power supplies and, in particular, to supplies having low noise and common mode current.
In many applications requiring low noise and low common mode current, large, heavy and expensive linear power supplies are used. A typical main component of these supplies are large, heavy and expensive transformers working at power main frequencies (e.g., low multiples of 60 hertz) that are specially designed for low noise and isolation. These transformers typically have large, heavy cores and many-turn (e.g., greater than 100) windings.
Switching power supplies often dispense with such transformers at the expense of additional noise in the DC output and degraded common mode performance. However, these supplies are usually smaller, lighter and less expensive.